Science Musings Blog

Sunday, June 28, 2009

The call of the wild

So what's happening to the cuckoo?

The call of the cuckoo -- that speaks its name -- used to be a familiar part of the spring and early summer here in Ireland. The letters column in the Irish Times invariably announced the first cuckoo, arriving, usually in April, after a long flight from South Africa. You heard it before you saw it -- cuc-coo -- and your heart made a little leap towards summer.

We don't hear the cuckoo any more. One more sad deletion from nature's prodigiality.

The cuckoo, of course, is a parasite. It disdains to build a nest or incubate a brood. Instead, the female cuckoo lays her egg in the nest of another species, removing an egg that belongs there. The unsuspecting mother bird, who went to all the trouble of building the nest, sits on the impostor egg along with her own. When the young cuckoo hatches, it tosses its "sibling" eggs or hatchlings out of the nest, thereby receiving the full attention of its foster parent.

Ah, isn't evolution grand. Imagine that cuckoo hatching being born with murder on its mind. It was all there in a "four-letter" code on the DNA, which makes proteins, which makes a bird brain intent on instant mayhem. TCCGAATGGGGATT=felony, so to speak. And if that doesn't make your head spin, nothing will.

So where are they? The cuckoos, I mean. Apparently, one problem is global warming. The parasitized species migrate from the Mediterranean basin. Because of changing climate, they are arriving in Northern Europe earlier and earlier, and starting families. By the time the cuckoos arrive all the way from the southern hemisphere -- unawares of the quickening tempo in northern climes -- the young of the usual surrogate parents have hatched and fledged. No nests in which to infiltrate an egg. No short-hop mothers to bamboozle.

Are we wrong to feel sorry for the felonious cuckoo? Or was a little intraspecies malfeasance an acceptable price to pay for that wonderful cuc-coo resounding over the gorsy moor, and the graceful shape of the long-haul trickster sculling the misty air?